Engine exhaust flame arrester



June l1, 1946. A. WILLIAMS, JR

ENGINE EXHAUST FLAME ARRESTER Filed Dec. 10, 1942 2 Sheets-Sheet 1 June 1.1, 1946. L. A. WILLIAMS, JR

ENGINE EXHAUST FLAME ARRESTER Filed' De. 1o, 1942 2 sheet-sneet 2 Patented June 11, 1946 ENGINE EXHAUST FLAME ARRESTER Lynn A. Williams, Jr., Northfield, Ill., assignor to Stewart-Warner Corporation,

corporation of Virginia Appneetmn December'n 1o, 1942, s eriei No. 468,460

(o1. so-31) 4 Claims. 1

The present invention relates to engine exhaust ame arresters, and is more particularly concerned with the provision of mechanism to prevent burning of exhaust gases at theoutlet end of aircraft engine exhaust pipes.

During the normal operation of an aircraft engine, the gasoline or other fuel is notcompletely converted into stable oxides Within the airplane engine, for instance, an appreciable quantity of carbon monoxide normally passes through the exhaust pipe. These exhaust gases are extremely hot, and as soon as they strike the atmosphere, the carbon monoxide combines with the oxygen in the air, thus producing a flame at the outlet end of the exhaust pipe.- The blue or purple flame thus normally present at the outlet of the exhaust pipe may be of no considerable importance in commercial airplanes. With military planes, however, the situation is entirely dierent, particularly with those it is intended to operate at night, because of the fact that the name at the end of the exhaust pipe renders the airplane visible to attacking planes at a considerable distance.

It is the principal object of the present invention to provide novel mechanism for preventing the burning of combustible gases at the outlet l end of an airplane exhaust pipe.

Yet another object of the present invention is to provide a novel flame arrester for an airplane exhaust pipe which prevents attacking planes from being able to nd their quarry by reliance upon the light normally present at the outlet end of an airplane exhaust pipe.

Still another object of the present invention is to provide novel mechanism for accomplishing the above without appreciably increasing the weight or parasite drag of the airplane provided with the device.

Yet another object of the present invention is to reduce the temperature of airplane exhaust gases suiiiciently so that carbon monoxide and other combustible substances normally present in exhaust gases will not burn when brought into the presence of the atmosphere,

Other objects and advantages will become apparent from the following description of a .preferred embodiment of my invention illustrated lin the accompanying drawings.

In the drawings, in which similar characters of reference refer to similar parts throughout the several views,

Fig. l is a side elevation of an engine exhaust flame arrester embodying the present invention;

Fig. 2 is a transverse sectional view through manifold.

Chicago, Ill., a

2 the device near one end thereof. It may be considered as taken in the direction of the arrows substantially along the lines 2-2 of Fig. 1; and Fig. 3 is a longitudinal sectional view through the device. It may be considered as taken in the to be located within the exhaust pipe either within the engine nacelle, or within that portion which passes rearwardly along the nacelle or beneath the lower surface of the wing. As shown in Fig. 1 it is comprised of a cylindrical portion I0 of approximately the same diameter as the exhaust pipe which is tted at its inlet side I2 to a pipe leading to the airplane engineexhaust Its opposite, or exhaust, end I4 is connected to a length of pipe which carries the products of combustion to any suitable location where they are passed into the atmosphere. Essentially, therefore, the cylindrical section I0 may be considered as a portion of the exhaust pipe.

The cylindrical portion I0 is equipped with a damper i6 of the buttery type, which, when in the position shown in Fig. 1,prevents the straightthrough ow of the exhaust gases. This damper is located approximately midway between the two ends of the device and is mounted upon a transverse control shaft or tube i8 journaled in bearing blocks 2li welded, or otherwise suitably secured, to the side wall of the cylindrical portion I0 at opposite sides.

A multiplicity of comparatively small diameter tubes 22 extends radially outwardly from, and is welded or otherwise suitably secured to, the lower suriace of the cylindrical portion Iii. These tubes are arranged in transverse rows as shown in Fig. 2 with their inner ends as clos together as ispractical.

A second row of similar tubes is similarly arranged in a transverse. row behind'the tubes in the rst row. In order t'o get the tubes in the second row as close as possible to those in the front row, the tubes in the two rows are staggered so that the inner ends of the second row tubes are secured to the cylindrical portion I0. in po? portion is'provided with an. opening to permitv the flow of products of combustion to, or from. the cylindrical portion through the tubesl 22.

The outer ends of the small diameter tubes 22 of the tubes in any one row, along the manifold,y

and back up into the cylindrical portion l through others of the tubes in the same row (Fig. 3). These manifolds are deeper in a radial direction in a position radially outwardly from the damper than they are at thev ends, because,-

as will be seen' presently, the quantity of gas flowing through the central portion of the manifolds is greater than that at the ends.'

The longitudinally extending, fan-shaped structure comprised of the tubes 22 and inaniare arranged in a plurality of longitudinally ex- L atmosphere. While the exhaust gases are g through the small diametertubes 22 and manifolds 2l, they are brought into heat exchange relation to the air flowing through they shroud 28. AThe temperature of the gases is," therefore, reduced considerably, at least' sufficiently to bring the temperature to such. a point that ignition wiilnot take place when the exhaust gases are mixed with an additional quantity'of fresh air at .the outlet end lof the engine exhaust pipe.

The gases, therefore, pass into the atmosphere without producing a flame which mightl betray ,the presence of the aircraft.

In the deviceshown, a large number of small diameter tubesA 22 are used, inasmuch as this device is intended to be operated in conjunction with an aircraft engine ofa high horsepower butput. Modifications, of course, will be made in the apparatus to with which it operates. When the device is used with smaller engines, less heat .exchange needs take place, and this can be accomplished in a number of manners, for instance, the tubes 22 can be shortened somewhat, or fewer numbers of these tubes can be used together with, or without, fewer numbers of the manifolds 2t. 0n the other hand. if the device is used with engines of higher folds 26 is enclosed within va sheet metal shroud '26, which embraces the fari-shaped structure both at its radially extending sides and 4around -the circumferential portion. The rearward portion of this shroud slopes'upwardly fromvits central point as indicated at 2B, so as closely to follow the tapered outer surfaces of the manifolds 26. The forward portion Sii of the shroud, y however, extends straight forwardly rather thanAO following the slope of the lower surfaces of the manifolds 24, and thus provides a scoop, which is located in the air stream. Air is caught in this scoop'and is forced to flow rearwardly around the tubes 22 and manifolds 2d and thence out at the rearward end of the shroud.

Preferably, the portions of the structure horsepower output, the unit shouldv be designed to have greater heat exchange capacity.

While I have shown and describeda particular embodiment of my invention, it will be apparent to those skilled in the art that numerous medincations and variations Vmay be made without dewhich become quite hot are formed of sheet metal and i tubing of stainless steel or some other heat and corrosion resisting material.' The shroud may be formed of aluminum or aluminum alloy. The manifolds may be constructed in any suitable parting from the'underlying principles of the invention. I therefore desire, .by the following claims, to include within the scope of .the invention all such modifications and variations by winch substantially the results thereof may be obtained. by substantially the same or equivalentl 1. An linternal combustion ene exhaust "restricting means and.others of said openings manner-thoseshown being formed in halgles and Joined along longitudinally extending Linedial lines by welding, thus providing ns 82 along the loweredges of the manifolds.

The device operates in the following manner: Under conditions where a ame at the exhaust pipe is not objectionable, the damper i6 maybe placed in its open position, thereby. permitting` the exhaust gases to flow straight through the cylindrical portion I0 to the atmosphere; When it is desired to eliminate the flame, such as when operating atnight over unfriendly territory, the

damper it is swung to its closed position, thus causing the products of combustion which enter the `cylindrical portion i@ to ow outwardly through the small diameter tubes 22 located upstream of the damper I6. These gases, after passing outwardly through these tubes,- flow rearwardly through the several manifolds 26 and back up into the cylindrical portion I@ through the group of small diameter tubes located downstream of the damper It; they then pass outl wardiy through the airplane exhaust pineto the being located downstream of said restricting means, a plurality of heat exchange tubes associated with said .openings mountedon said tubular portion, said openings and said tubes being arranged in rows longitudinal of said tubular portion, each of said rows being offset with respect to the adjacent row on either side, and plurality of manifolds, each 2. An internal combustion engine exhaust flame arrester comprising a. tubular portion adapted to be connected into-the exhaust line of an internal combustion engine, restricting means located within said tubular portion having a plu rality of openings in the side wall thereof, some of said openings being located upstream of said restrictingv means and others of said `openings being located downstream of said restricting means, a pluralityv of heat exchange tubes assoelated. with said openings mounted on said tubular portion; said openings and said tubes being arranged in rows longitudinal of said tubular portion, each of said rows being offset with re spect to the adjacent row on'either side, plurality of manifolds, each of said manifolds conthe outer ends of all ofthe tu a adapt it to the size of engine upstream of said y of said manifoldsiconnecting y the outer ends of all of the tubes in a single row.

single row, and means to direct a current oi' Acooling air over said tubes and said manifolds.

3. An internal combustion engine exhaust flame arrester comprising a tubular portion adapted to 4be connected into the exhaust line of an internal combustion engine, restricting means located within said tubular portion for `restricting theow of gas through said portion, said tubular portion having a plurality of openings in the side wall thereof, some of said openings being located upstream of said restricting means and others of said openings being located downstream of said restricting means, a plurality of heat exchange tubes associated with said openings mounted on said tubular portion, all of said tubes being of substantially the same length, said openings and. said tubes being arranged in rows longitudinal oi' said tubular portion, each of said rows lbeing offset with respect to the adjacent row on either side, and a plurality of tapered manifold sections, each of which has its greatest depth radially opposite said restricting means,

and each of said manifolds connecting the outer ends of lall of said tubes in a single: row.

, 4. An internal combustion engine exhaust ame arrester comprising a tubular portion adapted to be connected into the exhaust line' of an internal combustion engine, restricting means located within said tubular portion for restricting the flow of gas through said portion, said tubular portion having a plurality of openings in the side Wall thereof, some of said openings being located upstream of said restricting means and others of said openings being located downstream of said restricting means, a plurality of heat exchange tubes associated with said openings mounted on said tubular portion, all of said tubes' being of substantially the same length, said openings and said tubes arranged in rows longitudinal of said tubular portion, each of said rows being oilset with respect to the adjacent row on either side, a plurality of tapered manifold sections, each of which has its greatest depth radially opposite said restricting means, each of said manifolds connecting the outer ends of all of said tubes in a single row, and means to direct a. current of cooling air over said tubes and said manifolds.

LYNN A. WILLIAMS, JR. 

